Deep eutectic solvent-promoted sustainable synthesis of 4H-pyrimido [2,1-b] benzothiazoles via multicomponent reactions

Abstract

An eco-conscious one-pot three-component reaction approach has been designed for the synthesis of a diverse range of pyrimidobenzothiazoles, employing aldehydes, β-keto esters, and 2-aminobenzothiazole in choline chloride: malonic acid-based deep eutectic solvent (DES) medium. With the incorporation of biodegradable materials, cost-effectiveness, excellent product yields, high atom economy (AE), and low E-factor, this newly developed methodology stands out as a greener approach. Importantly, this protocol retained its high efficiency during scale-up studies, and also, DES medium can be recovered and reused up to four consecutive cycles without jeopardizing the product yield.